"When We Were Young" is a song by English singer Adele. It was released on 22 January 2016 by XL Recordings as the second single from her third studio album, 25 (2015). Adele co-wrote the song with Tobias Jesso Jr., while production of the track was provided by Ariel Rechtshaid. "When We Were Young" is a soul ballad, with lyrics that talk about reminiscing past memories with a loved one. Upon release, the song received positive response from music critics, who praised the song's lyrics and Adele's vocals.

"When We Were Young" was written by Adele and Tobias Jesso Jr., and produced by Ariel Rechtshaid. Rechtshaid was also the song's engineer, as well as the responsible for organ, glockenspiel, synthesizer, percussion and backing vocals. Jesso also provided backing vocals and played piano. The song also features bass, drums and guitar in its instrumentation. It was recorded at Dean Street Studios, London, and mixed at Capitol Studios, Los Angeles, and at Electric Lady Studios, New York. According to the sheet music published at Musicnotes.com by Universal Music Publishing Group, "When We Were Young" was written in common time in the key of E♭ major with a moderately slow tempo of 72 beats per minute. The song follows a chord progression of Cm–E♭/G–A♭–E♭/G–Fm7–E♭, and Adele's vocals span two octaves, from E♭3 to E♭5.

"When We Were Young" is a reflective soul ballad. Hattie Collins of i-D considered it "a 70s styled shimmery disco ballad." It is built around "somber piano chords," which according to Pitchfork's Jeremy Gordon, are "designed to show off her staggering, empathic voice." Gordon also perceived that her vocals switches "between husky crackle to a soaring delivery before eventually climaxing with a come-to-Jesus money note." As defined by Adele, "It's a very '70s singer-songwriter vibe. Which is Tobias' thing, which is why I picked him." Brian Hiatt of Rolling Stone found it to be similar to Elton John as well as Barbra Streisand's "The Way We Were". Bruce Handy of Vanity Fair agreed with Streisand's influence. The Fader's Owen Myers, in agreement with Rechtshaid and Adele, thought that the song reminded him of Gladys Knight. Collins, while also calling it "great big fat love song", opined that it "could be the album's 'Rolling In the Deep'."